On the North Sea coast in the modern day, the Doctor, Jamie and Victoria
learn of a series of mishaps and strange occurrences which has been
plaguing the oil refineries. They soon find that a form of intelligent
seaweed is rising up from the seabed, attempting to take over humanity --
and the invasion has already begun.

Production

On September 24th, 1964, Doctor Who story editor David Whitaker
rejected a proposal entitled “The Slide” from writer Victor
Pemberton. However, Pemberton had also submitted a version of the same
story idea, excluding Doctor Who elements, to BBC Radio, where it
was accepted by script editor Peter Bryant and eventually broadcast during
February and March 1966. “The Slide” concerned the efforts of
a sentient form of mud to take over a small village.

In 1967, both Pemberton and Bryant found themselves working on Doctor
Who. When Bryant, who was now the series' regular story editor,
received a trial promotion to producer during the summer, Pemberton -- his
assistant -- became the new story editor. Pemberton ultimately elected not
to continue in the position past those initial three months, but did take
the opportunity to suggest to Bryant that he write a new serial
resurrecting elements of “The Slide”. Instead of mud, however,
Pemberton took inspiration from the recent explosion of interest in
natural gas and decided that the invading force should instead be sentient
seaweed which thrived on the gas. This prompted a change in setting to a
North Sea refinery.

The recent explosion of interest in natural gas prompted a
change in setting to a North Sea refinery

“The Colony Of Devils” was commissioned by Bryant -- who had
temporarily returned to his post as story editor -- on October 5th.
Pemberton's adventure was targeted for production following The Enemy Of The World, as Serial QQ. However,
towards the end of 1967, Bryant finally received a permanent appointment
to the position of producer, to be replaced as story editor by Derrick
Sherwin. Sherwin was less enamoured of Pemberton's scripts, and felt that
several major changes needed to be made.

A subplot in episodes four and five was removed; this involved the Weed
attacking a conference, as it could now traverse the entirety of Great
Britain's network of natural gas pipelines. Victoria was to have killed
Oak's partner (at this point named Swan) with her screams in part five,
while Jamie was to have finally defeated the Weed at the story's climax by
playing his bagpipes. Sherwin had Swan survive -- although he generally
toned down the spookiness of the Oak and Swan double-act -- and used
Victoria's amplified screams to kill the Weed instead.

To provide time for these rewrites, “The Colony Of Devils” was
pushed back one spot in the recording schedule to become Serial RR, with
The Web Of Fear brought forward to replace
it. Pemberton was initially very unhappy about Sherwin's changes, and
considered having his name taken off the scripts. Ultimately, however,
Pemberton became satisfied with the story editor's decisions regarding
what turned out to be his only televised Doctor Who serial (a
subsequent idea, “The Eye In Space”, was rejected some months
later; Pemberton additionally wrote the LP Doctor Who and The
Pescatons for the Fourth Doctor and novelised both this and Serial
RR).

Another major change had to be made when it became known that Deborah
Watling would be leaving Doctor Who with “The Colony Of
Devils”. Sherwin duly inserted material into the scripts to build up
to Victoria's departure. As well, a few characters had to be renamed due
to similarities with figures from other recent adventures. Swan became
Quill (there having been a Swann in The Enemy Of The
World), while the presence of a Corporal Blake in The Web Of Fear caused the change of Blake in
“The Colony Of Devils” to Price. Less significantly, Lutyens
was modified slightly to Van Lutyens. Meanwhile, at Pemberton's
suggestion, the scene of the TARDIS landing was set at sea rather than on
a cliff edge as originally scripted. This was done to avoid duplicating a
similar materialisation at the end of The
Rescue three years earlier.

Derrick Sherwin inserted material to build up to
Victoria's departure

The director assigned to “The Colony Of Devils” was Hugh
David, who had handled The Highlanders the
previous season. This was also his final Doctor Who serial. He went
on to work on programmes like The Pallisers and The Man In The
Iron Mask in addition to forming his own production company, Wildacre
Productions. David died in the autumn of 1987.

Filming began with three days on location starting on February 4th, 1968.
David and his team had hoped to obtain permission to shoot at a real
refinery, but the Natural Gas Development Board denied this request.
Instead, the Red Sands Sea Fort in the Thames Estuary served as the
refinery platform. Filming also took place at Botany Bay in Broadstairs,
Kent for scenes on the beach. At the suggestion of production assistant
Michael Briant, the regular screwdriver which the script indicated the
Doctor should use in one of these sequences was replaced by a “sonic
screwdriver” (although the prop used was actually just a pen torch).
This device would become a recurring favourite of the Doctor's.

Work then moved to the Ealing Television Film Studios, spanning February
7th to 9th. Most of the scenes recorded at this time were those which
required use of the BBC's foam generator (Pemberton having envisaged the
Weed as dwelling within a covering of foam). A fourth location day
occurred on the 12th at the Denham Aerodrome in Denham, Buckinghamshire,
when various helicopter close-ups were filmed. At about this time, the
serial was retitled Fury From The Deep to avoid provoking
controversy by using the word “Devil”.

The first five episodes of Fury From The Deep followed the usual
Doctor Who production pattern and were taped on successive
Saturdays in Lime Grove Studio D. Part one went before the cameras on
February 24th. In addition, David's team returned to Ealing on March 5th
and 6th to film the climactic battle against the Weed for episode six.
Some of the material from part four was remounted alongside the recording
of the fifth installment on March 23rd.

March 29th marked the end of Deborah Watling's regular
involvement in Doctor Who

The next week saw taping shift to Studio 1 at the BBC's Television Centre.
The antiquated confines of Lime Grove D had never been suitable for
Doctor Who's complicated production, and the more modern Television
Centre would be the programme's home for most of the rest of the fifth
recording block. The change of scenery also meant that the taping of
episode six was scheduled for a Friday, March 29th.

Although Victoria would reappear in the first part of the next story,
The Wheel In Space (in material filmed as
part of Fury From The Deep), this marked the end of Deborah
Watling's regular involvement in Doctor Who. In addition to a
considerable body of theatrical work, Watling thereafter appeared in
television programmes such as The Newcomers and films including
Take Me High and That'll Be The Day. She would later reprise
her role as Victoria in the 1993 anniversary special Dimensions In Time and the video production
Downtime. Watling also played Auntie in the Doctor Who audio
drama Three's A Crowd from Big Finish Productions.